Apparatus and methods for dewatering sludge

ABSTRACT

An apparatus for dewatering sludge comprises a tank having an internal space divided by a dividing wall into an intake chamber and an extract chamber, an intake pipe connected to the intake chamber by an intake valve, a discharge pipe connected to the extract chamber by a discharge valve, and a transfer pipe providing fluid communication between the intake chamber and the extract chamber. The transfer pipe has first opening near the bottom of the intake chamber, and a second opening near the top of the extract chamber. A pump selectively creates positive and negative pressure within the intake chamber. A screen is positioned within the extract chamber between the second opening of the transfer pipe and the discharge pipe.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.16/624,023 filed on Dec. 18, 2019, which is the US national stage ofInternational Application No. PCT/CA2018/050760 filed on Jun. 21, 2018,which in turn claims the benefit of priority of U.S. Patent ApplicationNo. 62/523,033 filed on Jun. 21, 2017. U.S. patent application Ser. No.16/624,023, International Patent Application No. PCT/CA2018/050760 andU.S. Patent Application No. 62/523,033 are hereby incorporated byreference in their entirety.

TECHNICAL FIELD

The present disclosure relates to sewage sludge treatment, and inparticular to apparatus and methods for dewatering sludge and othermaterials.

BACKGROUND

Sewage sludge is composed of a mixture of solid and liquid. Separatingthe liquid from the solid allows the liquid to be reused and the solidto be more efficiently transported for treatment. Various systems forseparating liquids from sludge or other materials exist in the priorart, including: U.S. Pat. Nos. 3,677,409, 5,503,753, 4,816,167,3,028,011, US 2016/0289109, U.S. Pat. Nos. 5,462,661 and 4,021,347.

The inventor has determined a need for improved apparatus, methods andsystems for dewatering sludge and other materials.

SUMMARY

One aspect of the present disclosure provides an apparatus fordewatering sludge. The apparatus comprises a tank having an internalspace divided by a dividing wall into an intake chamber and an extractchamber, an intake pipe connected to the intake chamber by an intakevalve, a discharge pipe connected to the extract chamber by a dischargevalve, and a transfer pipe providing fluid communication between theintake chamber and the extract chamber. The transfer pipe has a firstopening near the bottom of the intake chamber, and a second opening nearthe top of the extract chamber. A pump selectively creates positive andnegative pressure within the intake chamber. A screen is positionedwithin the extract chamber between the second opening of the transferpipe and the discharge pipe.

Another aspect provides a method for dewatering sludge. The methodcomprises providing a tank having an internal space divided by adividing wall into an intake chamber and an extract chamber, an intakepipe connected to the intake chamber by an intake valve, a dischargepipe connected to the extract chamber by a discharge valve, a transferpipe providing fluid communication between the intake chamber and theextract chamber, with a first opening near the bottom of the intakechamber and a second opening near the top of the extract chamber, a pumpfor selectively creating positive and negative pressure within theintake chamber, and, a screen within the extract chamber positionedbetween the second opening of the transfer pipe and the discharge pipe.The method further comprises applying negative pressure to the intaketank by the pump with the intake valve open to suck a mixture of solidand liquid into the intake tank, through the intake pipe; injecting apolymer into the intake tank to coagulate the solids; and applyingpositive pressure to the intake tank by the pump with the intake valveclosed, the transfer valve open and the discharge valve open to forcethe mixture of coagulated solid and liquid through the transfer pipeinto the extract chamber, whereby the screen traps the coagulated solidsallowing liquid to pass through the discharge pipe.

Further aspects and details of example embodiments are set forth below.

DRAWINGS

The following figures set forth embodiments in which like referencenumerals denote like parts. Embodiments are illustrated by way ofexample and not by way of limitation in the accompanying figures.

FIG. 1 shows a cross section of an example dewatering apparatusaccording to one embodiment with the door closed.

FIG. 2 shows a cross section of the apparatus of FIG. 1 with the dooropen.

FIG. 3 shows an exterior view of a prototype dewatering apparatusaccording to one embodiment.

FIG. 4 shows a view of the interior of the extract chamber of theapparatus of FIG. 3 .

FIG. 5 shows the screen of the apparatus of FIG. 3 .

FIG. 6 shows the apparatus of FIG. 3 with the door open for removingsolids from the extract chamber.

FIG. 7 shows an example dewatering apparatus installed on a truck bedaccording to one embodiment.

FIG. 8 shows the apparatus of FIG. 7 with the door open and the truckbed raised on an incline.

FIG. 9 shows an example dewatering apparatus according to oneembodiment.

FIG. 10 is an exploded view of the apparatus of FIG. 9 .

FIG. 11 is a top view of the apparatus of FIG. 9 .

FIG. 11A is a sectional view taken along line A-A in FIG. 11 .

FIG. 11B is a side view of the apparatus of FIG. 9 .

FIG. 11C shows a detailed view of the area in circle C of FIG. 11A.

FIG. 11D shows a detailed view of the area in circle D of FIG. 11B.

FIG. 12 shows the transfer pipe of the apparatus of FIG. 9 .

FIG. 12A is a side view of the transfer pipe of FIG. 12 .

FIG. 12B is a front view of the transfer pipe of FIG. 12 .

DETAILED DESCRIPTION

The following describes example apparatus and methods for dewateringsludge.

For simplicity and clarity of illustration, reference numerals may berepeated among the figures to indicate corresponding or analogouselements. Numerous details are set forth to provide an understanding ofthe examples described herein. The examples may be practiced withoutthese details. In other instances, well-known methods, procedures, andcomponents are not described in detail to avoid obscuring the examplesdescribed. The description is not to be considered as limited to thescope of the examples described herein.

FIG. 1 and FIG. 2 show a cross section of an example apparatus 100 fordewatering sludge. The apparatus 100 comprises a tank 102 having aninternal space divided by a dividing wall 104 into an intake chamber 106and an extract chamber 108. A pump 110 is connected to the intakechamber 106 to selectively create positive and negative pressure in theintake chamber 106. The pump 110 may have a primary filter 112 and asecondary filter 114. The pump 110 and filters 112/114 may besubstantially the same as those in standard vacuum trucks. An intakepipe 116 having an intake valve 117 is connected to the intake chamber106 for drawing sludge or other materials into the tank as discussedbelow. A coarse intake filter (not shown), such as for example acanister filter, may be provided on the intake pipe to prevent large(e.g. greater than about ½ inch diameter) solids from entering theintake chamber. A discharge pipe 118 having a discharge valve 119 isconnected to the extract chamber 108 for discharge of liquids from thetank as discussed below.

A transfer pipe 120 provides fluid communication between the intakechamber 106 and the extract chamber 108. The transfer pipe 120 has afirst opening 122 near the bottom of the intake chamber 106 and a secondopening 124 near the top of the extract chamber 108. The dividing wall104 has an opening near the top thereof to permit the transfer pipe 120to pass through, but otherwise seals off the extract chamber 108 fromthe intake chamber 106.

A screen 130 is positioned within the extract chamber 108 between thesecond opening 124 of the transfer pipe 120 and the opening of thedischarge pipe 118. In some embodiments, as illustrated in FIG. 1 , thescreen 130 may substantially conform to the shape of the extract chamber108 and may have a hole for the second opening 124 of the transfer pipe120. Details of an example screen are discussed below with reference toFIG. 5 . In the illustrated example, the end portion of the extractchamber 108 of the tank 102 comprises a door 140 which may be opened topermit access to the extract chamber 108 for removal of solids. Thescreen 130 comprises an open end with a generally circular rim 132 whichpresses up against a rim 142 of the door 140 when the screen 130 is inplace and the door 140 is closed. The door 140 may be held closed by abuckle latch 144, as shown in FIG. 2 , or any other suitable mechanism.The tank 102 may also be provided with a relief valve 152 and pressuregauge 154. In some embodiments, the tank 102 also has an access hatch156 (see FIG. 1 ) in an upper portion of the intake chamber 106 forproviding access thereto, and a cleaning port 158 (see FIG. 1 ) in alower portion of the intake chamber 106 near the bottom of the transferpipe 120 and the dividing wall 104. The hatch 156 and/or port 158 may beat different locations in other embodiments.

In the illustrated example, the transfer pipe 120 is at an approximately45 degree angle from the horizontal. The transfer pipe 120 may be at adifferent angle from the horizontal in other embodiments. As usedherein, the term “horizontal” refers to a direction parallel to thelongitudinal axis of the tank 102, such that the absolute angle of“horizontal” may change as the orientation of the tank 102 changes. Thisconfiguration permits any sludge or other materials remaining in theintake chamber 106 or transfer pipe 120 to fall into the extract chamber108 when the tank 102 is tipped for dumping or cleaning as discussedbelow. In the illustrated example, an angled portion 105 of the dividingwall 104 is also at an approximately 45 degree angle from thehorizontal. The dividing wall 104 and transfer pipe 120 may bedifferently configured in other embodiments (for example, the dividingwall may extend vertically upward from the first opening at the bottomend of the transfer pipe in some embodiments, or the dividing wall maycomprise a curved wall and the transfer pipe may be substantiallyvertical, as discussed below with reference to FIGS. 9-12 ), and thusthe intake and extract chambers 106 and 108 and screen 130 may havedifferent shapes in different embodiments.

FIGS. 3, 4 and 5 show features of a prototype dewatering apparatus 100Aaccording to one embodiment. Elements of the prototype apparatus 100A ofFIGS. 3-5 are correspondingly numbered with corresponding elements ofapparatus 100 of FIG. 1 . FIG. 4 shows a view of the interior of theextract chamber 108A of the tank 102A of apparatus 100A of FIG. 3 ,wherein the second opening 124A of the transfer pipe 120A is shownprotruding through the dividing wall 104A. FIG. 5 shows the screen 130Aof the apparatus 100A of FIG. 3 . The screen 130A comprises a rim 132Awith a structural support frame 134A extending therefrom. A web 136A ofwire mesh and fine screen material is supported by the rim 132A andframe 134A. FIG. 6 shows the apparatus 100A of FIG. 3 with the door 140Aopen for removing solids from the extract chamber.

In some embodiments, dewatering apparatus 100/100A may be installed on atruck bed (as shown in FIGS. 7 and 8 ), on a trailer or any othertransport platform to move the apparatus to and from worksites. Theoperation of the example apparatus 100 of FIGS. 1 and 2 is shown in FIG.7 and FIG. 8 with the apparatus 100 in different orientations and thedoor 140 in a closed position and open position. In some embodiments,the apparatus 100 may move to a different orientation, for example byraising a truck bed on an incline, as shown in FIG. 8 with the door inan open position.

To commence sludge intake, the intake pipe 116 is connected to a hose orthe like (not shown) that is placed into a source of sludge. Negativepressure is applied to the intake chamber 106 by the pump 110, with theintake valve 117 open, causing the sludge to be drawn into the intakechamber 106 through the intake pipe 116. A polymer is injected into theintake chamber 106, for example through a separate polymer injectionvalve (not shown). Injecting a suitable polymer into the intake chamber106 causes solids in the sludge to coagulate into clumps as known in theart.

Once the sludge is in the intake chamber 106, the intake valve 117 isclosed and positive pressure is applied to the intake chamber 106 by thepump 110, with the discharge valve 119 open. This positive pressurecauses the sludge to be forced into the first opening 122, up thetransfer pipe 120, and through the second opening 124 into the extractchamber 108. After the sludge passes through the second opening 124 intothe extract chamber 108 the screen 130 separates the solid and liquid byblocking the solid and permitting the liquid to pass through the screen130 and out through the discharge pipe 118.

In some embodiments, once liquid has been discharged, the door 140 isopened and the solids caught by the screen 130 within the extractchamber 108 are manually removed by shoveling or other means. In someembodiments, the tank 102 may be tipped for dumping, for example byraising a truck bed on an incline as shown in FIG. 8 .

FIGS. 9-11D show another example apparatus 200. Elements of theapparatus 200 of FIG. 9-11D are correspondingly numbered withcorresponding element of apparatus 100 of FIG. 1 , in the form of 2 xxinstead of 1 xx. The apparatus 200 operates substantially similarly tothe apparatus 100 of FIG. 1 but differs from apparatus 100 in a numberof details, including the shape of the intake chamber 206, extractchamber 208, dividing wall 204, transfer pipe 220 and screen 230, asdiscussed below. In the example of FIGS. 9-11D, elements of theapparatus 200 constructed from steel or other rigid materials are shown,but various flexible hoses connecting pipes of the apparatus 200 to eachother are not shown, as described below.

The apparatus 200 comprises a tank 202 having an internal space dividedby a dividing wall 204 into an intake chamber 206 and an extract chamber208. In this embodiment the dividing wall 204 does not have an angledsection, but is instead curved in a manner similar to the opposite sideof the intake chamber 206 such that the intake chamber 206 itself is inthe form of a pressure tank. In the illustrated example, the intakechamber 206 has a baffle assembly 207 (see FIG. 11A) therein forreducing sloshing of material within the tank 202 when a truck isdriving with the apparatus 200 mounted thereon.

The tank 202 is mounted on a deck assembly 250 configured to be mountedon a truck. A sill assembly 252 is attached to the bottom of the tank202, and the sill assembly 252 is pivotally coupled to hinge pins 254 atthe rear of the deck assembly 250 such that the tank 202 may be tiltedup at the front for dumping. The sill assembly 252 may be higher at thefront that the back such that the tank 202 is at a slight incline, asbest seen in FIGS. 11A and 11B.

A pump (not shown) is connected to the intake chamber 206 to selectivelycreate positive and negative pressure in the intake chamber 206. In theillustrated example the pump is configured to be coupled to a primaryfloat trap 212 though a first connecting pipe 211A mounted on the sideof the tank 202 and a second connecting pipe 211B mounted on the deckassembly 250. Flexible hoses (not shown) are connected between theprimary float trap 212 and the first connecting pipe 211A, between thefirst connecting pipe 211A and the second connecting pipe 211B, andbetween the second connecting pipe 211B and the pump. The pump may alsohave one or more secondary filters (not shown) associated therewith. Thepump, float trap 212 and filters may be substantially the same as thosein standard vacuum trucks.

An intake pipe 216/216A/216B having an intake valve 217 is connected tothe intake chamber 206 for drawing sludge or other materials into thetank as discussed below. In the illustrated example, a coarse intakefilter 215, such as for example a canister filter, is connected byflexible hoses (not show) between a first portion 216 of the intake pipeand a second portion 216A of the intake pipe to prevent large (e.g.greater than about ½ inch diameter) solids from entering the intakechamber. The second portion 216A of the intake pipe is connected byanother flexible hose (not shown) to a third portion 216B of the intakepipe that has the intake valve 217. A discharge pipe 218 having adischarge valve 219 is connected to the extract chamber 208 fordischarge of liquids from the tank as discussed below.

With reference to FIGS. 10, 11A, 11C, 12, 12A and 12B, the apparatus 200comprises a transfer pipe 220 which is generally vertically oriented(with a bend near the top thereof such that the top is generallyhorizontal) when the tank 202 is horizontal. The transfer pipe 220provides fluid communication between the intake chamber 206 and theextract chamber 208. The transfer pipe 220 has a first opening 222 nearthe bottom of the intake chamber 206 and a second opening 224 near thetop of the extract chamber 208. The dividing wall 204 has an openingnear the top thereof to permit the transfer pipe 220 to pass through,but otherwise seals off the extract chamber 208 from the intake chamber206. A screen 230 is positioned within the extract chamber 208 betweenthe second opening 224 of the transfer pipe 220 and the opening of thedischarge pipe 218. In some embodiments, the screen 230 maysubstantially conform to the shape of the extract chamber 208. Thescreen 230 has a hole for receiving the upper end of the transfer pipe220 such that the second opening 224 is inside of the screen 230. In theillustrated example, a snorkel assembly 226 is attached to the secondopening 224 of the transfer pipe 220, as described below.

The first opening 222 at the bottom of the transfer pipe 220 has afunnel-type structure 223 for guiding fluid into the transfer pipe 220.As best seen in FIG. 12A, the bottom of the funnel-type structure 223 isshaped to conform to the bottom of the tank 202 and bottom portion ofthe dividing wall 204 where it meets the tank 202. A flange 225 isprovided near the second opening 224 of the transfer pipe 220. Theflange 225 is configured to be bolted to a corresponding flange 227 ofthe snorkel assembly 226, which is attached to the screen by a sealinggasket 228. The snorkel assembly 226 also comprises a floating ballvalve 229 which allows material to enter the extract chamber 208 fromthe transfer pipe 220 when positive pressure is applied to the intakechamber 206, and prevents material from leaving the extract chamber 208through the transfer pipe 220 when negative pressure is applied to theintake chamber 206.

In the illustrated example, the end portion of the extract chamber 208of the tank 202 comprises a door 240 which may be opened to permitaccess to the extract chamber 208 for removal of solids. The screen 230comprises an open end with a generally circular rim 232 which presses upagainst a rim 242 of the door 240 when the screen 230 is in place andthe door 240 is closed. The screen 230 may have pins 231 on opposedsides thereof configured to be received in pin receivers 233 (see FIG.10 ) on the inside of the extract chamber 208. One or more sealing rings(not shown) may be provided at the interface between the rim 242 of thedoor 240 and the rim 232 of the screen. The door 240 may be held closedby a plurality of latches 244 or any other suitable mechanism.

The tank 202 may also be provided with a relief valve (not shown) and apressure gauge (not shown). In the illustrated example, the tank 202 hasan access hatch 256 (see FIGS. 11 and 11B) at one of the sides of theintake chamber 206 for providing access thereto, and the door 240 has adump port 258 in a lower portion thereof. The hatch 256 and/or dump port258 may be at different locations in other embodiments. The dump out 258may be referred to as an access hatch, a mud gate, cleanout, and so on.

In operation, to commence sludge intake, the intake pipe 216B isconnected to a hose or the like (not shown) that is placed into a sourceof sludge. Negative pressure is applied to the intake chamber 206 by thepump, with the intake valve 217 open, causing the sludge to be drawninto the intake chamber 206 through the intake pipe 216. A polymer isinjected into the intake chamber 206, for example through a separatepolymer injection valve (not shown). Injecting a suitable polymer intothe intake chamber 206 causes solids in the sludge to coagulate intoclumps as known in the art. Once the sludge is in the intake chamber206, the intake valve 217 is closed and positive pressure is applied tothe intake chamber 206 by the pump, with the discharge valve 219 open.This positive pressure causes the sludge to be forced into the firstopening 222, up the transfer pipe 220, and through the second opening224 into the extract chamber 208. After the sludge passes through thesecond opening 224 into the extract chamber 208 the screen 230 separatesthe solid and liquid by blocking the solid and permitting the liquid topass through the screen 230 and out through the discharge pipe 218.

It will be appreciated that numerous specific details are set forth inorder to provide a thorough understanding of the exemplary embodimentsdescribed herein. However, it will be understood by those of ordinaryskill in the art that the embodiments described herein may be practicedwithout these specific details. In other instances, well-known methods,procedures and components have not been described in detail so as not toobscure the embodiments described herein. Furthermore, this descriptionis not to be considered as limiting the scope of the embodimentsdescribed herein in any way, but rather as merely describingimplementation of the various example embodiments described herein.

The description provides many example embodiments of the inventivesubject matter. Although each embodiment represents a single combinationof inventive elements, the inventive subject matter is considered toinclude all possible combinations of the disclosed elements. Thus if oneembodiment comprises elements A, B, and C, and a second embodimentcomprises elements B and D, then the inventive subject matter is alsoconsidered to include other remaining combinations of A, B, C, or D,even if not explicitly disclosed.

Although the embodiments have been described in detail, it should beunderstood that various changes, substitutions and alterations can bemade herein. Moreover, the scope of the present application is notintended to be limited to the particular embodiments of the process,machine, manufacture, composition of matter, means, methods and stepsdescribed in the specification. As can be understood, the examplesdescribed above and illustrated are intended to be exemplary only.

As will be apparent to those skilled in the art in light of theforegoing disclosure, many alterations and modifications are possible tothe methods and systems described herein. While a number of exemplaryaspects and embodiments have been discussed above, those of skill in theart will recognize certain modifications, permutations, additions andsub-combinations thereof. It is therefore intended that the followingappended claims and claims hereafter introduced are interpreted toinclude all such modifications, permutations, additions andsub-combinations as may reasonably be inferred by one skilled in theart. The scope of the claims should not be limited by the embodimentsset forth in the examples, but should be given the broadestinterpretation consistent with the foregoing disclosure.

The present disclosure may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive.

The invention claimed is:
 1. A method for dewatering sludge comprising:providing an apparatus comprising a tank having an internal spacedivided by a dividing wall into an intake chamber and an extractchamber; an intake pipe connected to the intake chamber by an intakevalve; a discharge pipe connected to the extract chamber by a dischargevalve; a transfer pipe providing fluid communication between the intakechamber and the extract chamber, with a first opening near the bottom ofthe intake chamber and a second opening near the top of the extractchamber; a pump for selectively creating positive and negative pressurewithin the intake chamber; and, a screen within the extract chamberpositioned between the second opening of the transfer pipe and thedischarge pipe, applying negative pressure to the intake chamber by thepump with the intake valve open to suck a mixture of solid and liquidinto the intake chamber, through the intake pipe; injecting a polymerinto the intake tank to coagulate the solids; and applying positivepressure to the intake chamber by the pump with the intake valve closedand the discharge valve open to force the mixture of coagulated solidand liquid through the transfer pipe into the extract chamber, wherebythe screen traps the coagulated solids allowing liquid to pass throughthe discharge pipe, wherein an end of the tank adjacent to the extractchamber comprises a door having a rim, and wherein the screen conformsto the shape of the extract chamber and comprises an open end with acircular rim which presses against the rim of the door when the door isclosed, the method comprising opening the door to remove solids from theextract chamber without removing the screen.